Many surgical procedures require the use of catheters to provide local fluid communication to a particular site within a patient. Such fluid communication may provide means for administering medication directly to the site, or may provide a pressure relief passage to relieve gas or fluid pressure generated within the body cavity. Numerous other uses of catheters are commonplace in modern medicine.
Certain medical procedures require the use of catheters to obtain biological samples of an infected site of the patient. In this way, the cause of certain medical conditions and ailments may be identified and subsequently properly treated.
During their placement, however, these catheters must typically traverse contaminated areas and therefore have the potential of carrying some contaminated material to a desired site which is intended for treatment and/or diagnosis. The unexpected contamination of the desired site may cause inaccuracies in the diagnosis and therefore also in the prescribed treatment.
Moreover, as any open-ended catheter is forced through body tissue, the relatively sharp rim of the tubular opening of its fluid lumen often "cores" a portion of the tissue which results in the clogging of the fluid lumen. The tissue lodged within the fluid lumen either prevents fluid flow through the lumen or is inadvertently dislodged into the body once positive fluid pressure is applied. Once dislodged within a patient's body, such loose tissue pieces create, at the very least, undesirable and unnecessary concern. The dislodged "cored" tissue can contaminate and damage healthy tissue, cause numerous complications and in some situations, such as an embolus carried by the blood stream, the tissue piece may even result in the patient's death.
To help prevent the accidental spread of infection throughout a patient's body catheters have been proposed wherein the distal opening of the catheter is covered with a water-soluble cap. One such protective cap is disclosed by U.S. Pat. No. 3,736,939 issued to Taylor. The cap is primarily used to prevent the catheter from "coring" the tissue as it is forced through a patient's body. The cap, which provides a rounded distal end to the catheter, dissolves within the body after a predetermined period. Once the cap dissolves, the fluid passage of the catheter is exposed, thereby allowing fluid communication with the body tissue. Unfortunately, the cap disclosed in U.S. Pat. No. 3,736,939 and other similar caps of the prior art are inherently bulky and thereby restrict the degree of flexibility, maneuverability and accessibility of the catheter within the patient or within other surgical instruments used in certain medical procedures, such as a bronchoscope used to diagnosis and treat pulmonary diseases.
A common medical procedure for diagnosing pulmonary diseases, specifically pneumonia, includes the bronchoalveolar lavage (BAL) of a lung segment. In this procedure, the tip of a fiberoptic bronchoscope is wedged into a sampling position in the airway of a lung segment. Lavage fluid is then introduced into, and then removed from, the lung segment of interest. Material collected from the lung segment along with the retrieved lavage fluid can yield important diagnostic information regarding a particular infection or condition.
Unfortunately, in order for the bronchoscope to reach the bronchial tree, it must traverse the oropharynx or the endotracheal tube where resident bacteria are likely to be introduced into the open distal-end suction channel of the instrument, usually in the form of mucus. Once in position, as the lavage solution is passed directly through the suction channel of the bronchoscope, the "cored-plug" of mucus will be forced from the suction channel and directly into the lung segment being sampled. The foreign mucus will contaminate the lung segment and the lavage solution, and render any resulting diagnostic data frequently inaccurate.
A protected catheter is disclosed in a medical paper entitled "PROTECTED BRONCHOALVEOLAR LAVAGE, A New Bronchoscopic Technique to Retrieve Uncontaminated Distal Airway Secretions", written by G. Umberto Meduri, David H. Beals, Amado G. Maijub, and Vickie Baselski, dated April, 1991. The catheter disclosed by this paper includes a thin polyethylene glycol diaphragm formed across its distal tip "to prevent contaminants from entering the system". The paper fails to disclose the method for forming the thin protective diaphragm.
In another related procedure, a balloon-tipped catheter is passed through the suction channel of the bronchoscope. The catheter is positioned within the airway of a lung segment to be sampled. The balloon of the catheter is inflated to isolate one particular lung segment from the others. Lavaging is then performed through the fluid lumen of the balloon-tipped catheter. Unfortunately, a similar problem occurs as the catheter passes through the suction channel of the bronchoscope. The unprotected distal end of the fluid lumen of the catheter will "core" through the mucus-borne contaminants located at the distal end of the suction lumen, resulting in similarly contaminated sampling and inaccurate diagnostic data.
In several studies, oropharyngeal and tracheobronchial contaminants, which are present in high concentration in the upper respiratory tract of patients, were frequently found in BAL specimens taken from the patients who were not otherwise infected. Contamination of bronchoalveolar lavage from upper respiratory tract secretions using these prior art non-protected techniques, has limited the use of bronchoalveolar lavage in diagnosing bacterial pneumonia.
Therefore, it is an object of the invention to provide a device, and a method for its use, which effectively eliminates the above mentioned "coring" problems associated with prior art devices.
It is another object of the invention to provide a device and method for its use which effectively decreases or eliminates contamination of the respiratory tract secretions retrieved with BAL.
It is another object of the invention to provide a catheter which retains its non-contaminated integrity for fluid communication even after traversing contaminated areas.